Low voluntary calcium intakes have been implicated in most of the chronic diseases afflicting Americans. There have been many recommendations to increase calcium intake, but almost no research to understand why calcium intakes are so low. This oversight is addressed by the current project. The overall goal is to characterize the behavioral, physiological and genetic mechanisms underlying the appetite to consume calcium. The emphasis of this application is on the genetics of calcium intake. Specifically, the method of quantitative trait locus (QTL) analysis will be used to identify the genes involved in the control of calcium intake in mice. This will involve (1) producing segregating hybrid mice from parental strains differing in calcium intake, (2) conducting genome screens and using lineage analysis to identify QTLs underlying the variation in calcium intake, (3) defining the QTLs with more precision by fine genetic mapping and the production of congenic lines of mice differing in calcium intake, and (4) using in silico methods to identify the genes involved. Given the many similarities between the mouse and human genome, the discovery of genes involved in calcium intake in mice will have direct relevance for the control of calcium intake by humans and thus the many diseases associated with low calcium intake.